An essential water-soluble B vitamin that acts as a coenzyme for fatty acid synthesis, energy metabolism, and keratin production.
What it is
Biotin (vitamin B7 or vitamin H) is a water-soluble B-complex vitamin consisting of an ureido ring fused with a tetrahydrothiophene ring. In dietary supplements, it is provided as pure D-biotin, the biologically active stereoisomer. Biotin functions as an obligate covalent cofactor for five mitochondrial and cytosolic carboxylase enzymes essential for gluconeogenesis, fatty acid synthesis, and amino acid catabolism in human cells.
Also known as: Vitamin H, D-Biotin
What it does
- Acts as an essential carboxylase coenzyme for cellular energy production and macronutrient metabolism.
- Supports keratin infrastructure, promoting strong hair, healthy skin, and resilient nails.
- Maintains normal nervous system function and gene expression through histone biotinylation.
Amplified by probiotics
While dietary biotin is absorbed in the upper small intestine via sodium-dependent multivitamin transporters (SMVT), substantial quantities of endogenous biotin are synthesized de novo by colonizing probiotic microbes—specifically Bifidobacterium infantis, Bifidobacterium longum, and Lactobacillus reuteri—in the large intestine. Patented microencapsulation delivers live probiotic strains safely through gastric acid into the distal colon, significantly elevating local luminal biotin concentrations. Specialized SMVT receptors expressed on colonic epithelial cells absorb this bacterial biotin directly into colonic enterocytes. Furthermore, probiotic-generated short-chain fatty acids (SCFAs, mainly acetate and butyrate) lower luminal pH, nourish enterocytes, and upregulate host SMVT transporter gene expression, creating a synergistic feedback loop that maximizes host biotin bioaccessibility and systemic metabolic utilization.
Typical dose
30–3,000 µg/day
The evidence
Evidence: strongClinical trials demonstrate that oral biotin supplementation reverses deficiency symptoms, improves brittle nail thickness, and supports mucosal integumentary health. Human physiological studies establish its role in carboxylase activation and systemic lipid synthesis (Patel et al. 2017, Skin Appendage Disord; Zempleni et al. 2009, Biofactors).
Safety & who should check first
Extremely safe with no tolerable upper intake limit (UL) due to high renal excretion. High oral supplemental doses (>5 mg/day) can interfere with immunoassay lab tests (e.g. thyroid, troponin).